1. Field of the Invention
An odor transducer for the detection and measurement of foreign matter contained in a fluid substance, particularly atmosphere.
2. Description of the Prior Art
In recent years there has been a rapid increase in the knowledge concerning the deleterious effects of air pollution upon animal life. Sophisticated systems for the removal of pollutants from the atmosphere have been developed. Such systems include prior art devices and systems for measuring the amounts of such pollutants.
Generally speaking, air pollution is largely made up of small particulate matter. These particles are usually in the submicron range and are suspended in the fluid atmosphere. In order to operate many of the pollution removal systems at or near maximum efficiency, it is necessary to know the concentration of pollutants in the atmosphere. Prior art methods of measuring the pollutant concentration have typically used sensing elements or transducers whose resistance varies in some proportion to the pollutants present. Usually, the transducer is one arm of a bridge. This method of measuring pollutants is complex in that the bridge circuit requires continual balancing by trained personnel.
Other pollutant measuring devices use operational amplifiers in a feedback configuration. This has the advantage of being relatively easy to operate. However, the output of these devices is a non-linear function of the concentration. The non-linear display of concentration is awkward and difficult to work with in a pollution detector system.
In operation, it is well recognized that, the signal from the detection system can be used to control the pollution abatement device. In this application, a non-linear signal causes problems in controlling the abatement system. Also, if the output is merely to be displayed or recorded, a non-linear signal requires scale changes and constant monitoring to assure a readable scale is being used.
It is desirable to have the concentration of pollutants displayed as a linear function by a relatively simple, inexpensive and easy to operate sensing device.